[erlang-questions] Tuples referencing each other problem

Brady Powers <>
Thu Sep 21 17:20:58 CEST 2017

 When I think about a data structure that needs to be traversed in both directions, I immediately think of a zipper.

It might not be appropriate, it's just where my mind goes.     On Thursday, September 21, 2017, 10:24:17 AM EDT, Grzegorz Junka <> wrote:  
Many thanks to all for your responses and suggestions.
To answer your question Richard, I don't actually need a cyclical structure. As I mentioned, this is a simplification of a more specific problem. I didn't want to describe all the specifics to ask a question. I need to design a tree, a variant of a HAMT tree, but which can be traversed in both directions, from the root to leafs and from leafs to the root (independently, i.e. starting from a reference to a leaf rather than recursively). Tuples that reference each other is one solution but not the only one fortunately, i.e. I can add ids to each node and use another data structure to store the mapping id-node, then store the id of the parent in the child.
Thank you for the pointer to the book.
 On 18/09/2017 00:53, Richard A. O'Keefe wrote:
On further reflection, I suppose I should ask: 
  Why is it that you think you need cyclic structures? 
  What do you actually want to *do* with them? 
 As a matter of curiosity, have you read Okasaki's 
 book on functional data structures? 
 (Didn't someone convert Okasaki's Edison library 
 to Erlang at some point?  What happened to that?) 
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